当前，世界所面临的重大环境问题的中心问题是______。
参考答案：人口问题
下列哪种物质不是糖异生的原料（）
A.丙酮酸
B.核酸
C.氨基酸
D.草酰乙酸
E.乳酸
----Does Jim do his new job well?
---- __________ his old job.
----How stupid! I fear there's no hope for him.
A．No better than
B．Not better than
C．No so well as
D．No as well as
